concealment writes: "At the end of August this year, the US Department of Transport's National Highway Traffic Safety Administration (NHTSA) and the US Environmental Protection Agency (EPA) announced new standards to significantly improve the fuel economy of cars and light trucks by 2025. Last week, we took a look at a range of recent engine technologies that car companies have been deploying in aid of better fuel efficiency today. But what about the cars of tomorrow, or next week? What do Detroit, or Stuttgart, or Tokyo have waiting in the wings that will get to the Obama administration's target of 54.5 miles per gallon (mpg) by 2025?"